Precompute whether modules respond to batch notification methods

Summary:
public

Looping through every `RCTModuleData` to check whether the module responds to `-batchDidComplete` or `-partialBatchDidFlush` is unnecessarily expensive. We can cache the answer at the time that the module instance is actually initialized.

Reviewed By: tadeuzagallo

Differential Revision: D2717594

fb-gh-sync-id: 274a59ec2d6014ce18c93404ce6b9940c1dc9c32

React/Base/RCTBatchedBridge.m

@@ -804,7 +804,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithBundleURL:(__unused NSURL *)bundleUR
 - (void)partialBatchDidFlush
 {
   for (RCTModuleData *moduleData in _moduleDataByID) {
-    if (moduleData.hasInstance && [moduleData.instance respondsToSelector:@selector(partialBatchDidFlush)]) {
+    if (moduleData.implementsPartialBatchDidFlush) {
       [self dispatchBlock:^{
         [moduleData.instance partialBatchDidFlush];
       } queue:moduleData.methodQueue];
@@ -816,7 +816,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithBundleURL:(__unused NSURL *)bundleUR
 {
   // TODO: batchDidComplete is only used by RCTUIManager - can we eliminate this special case?
   for (RCTModuleData *moduleData in _moduleDataByID) {
-    if (moduleData.hasInstance && [moduleData.instance respondsToSelector:@selector(batchDidComplete)]) {
+    if (moduleData.implementsBatchDidComplete) {
       [self dispatchBlock:^{
         [moduleData.instance batchDidComplete];
       } queue:moduleData.methodQueue];

React/Base/RCTModuleData.h

@@ -63,4 +63,15 @@
  */
 @property (nonatomic, copy, readonly) NSArray *config;
 
+/**
+ * Whether the receiver has a valid `instance` which implements -batchDidComplete.
+ */
+@property (nonatomic, assign, readonly) BOOL implementsBatchDidComplete;
+
+/**
+ * Whether the receiver has a valid `instance` which implements
+ * -partialBatchDidFlush.
+ */
+@property (nonatomic, assign, readonly) BOOL implementsPartialBatchDidFlush;
+
 @end

React/Base/RCTModuleData.m

@@ -39,6 +39,8 @@
   if ((self = [super init])) {
     _instance = instance;
     _moduleClass = [instance class];
+
+    [self cacheImplementedSelectors];
   }
   return self;
 }
@@ -62,10 +64,18 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init);
 
     // Initialize queue
     [self methodQueue];
+
+    [self cacheImplementedSelectors];
   }
   return _instance;
 }
 
+- (void)cacheImplementedSelectors
+{
+  _implementsBatchDidComplete = [_instance respondsToSelector:@selector(batchDidComplete)];
+  _implementsPartialBatchDidFlush = [_instance respondsToSelector:@selector(partialBatchDidFlush)];
+}
+
 - (void)setBridgeForInstance:(RCTBridge *)bridge
 {
   if ([_instance respondsToSelector:@selector(bridge)]) {